This paper outlines the role of the English language in the arena of international business communication, in particular, how this role is reflected in the English language communication by Thai automotive engineers. The study was designed with an interdisciplinary approach which integrates Global English and Business Communication research frameworks. It was conducted through interviews with the executive staff from an automotive manufacturer in Thailand and the foreign professionals who co-work with this transnational organization, and data collected thereof were analyzed through content analysis. The finding of the study suggests that professionally adequate proficiency in English communication has not only become a global passport for the engineers but also a source of power to function competitively in international business. The capacity to communicate orally in English was found to be the greatest challenge for Thai engineers in balancing their daily work commitments and their professional advancement. And the results of this study also show that the attempts of English language learning practices in the workplace in Thailand’s engineering workplace have posed more questions than answers in responding to this global challenge.